Soil Moisture Inversion Model Based On The Comprehensive Monitoring Of The Spring Drought In Henan Province

Drought is a common natural disaster, which may seriously threaten our country’s agricultural production. This in turn may adversely affect the development of both micro and macro economy in China.As Henan Province has been well documented to be a susceptiple location to spring drought.Precipitation in Henan quite different in different seasons, which have led to meteorological disasters occur frequently throughout the year in Henan.Especially, the spring drought occur most frequently.At present, most of the research is based on a single method in Henan Province,the combination of various drought indices is still rare.Therefore, this paper use meteorological, agricultural and remote sensing drought indices, build a soil moisture inversion model based on comprehensive drought monitoring, which is in favor of the distribution of the drought.The main conclusions are as follows:(l)From the point of view of the meteorological drought monitoring:mild drought is mostly likely to occur, the extreme drought probability of occurrence is minimum.Conculsively, spring drought frequency in northern and eastern in Henan is very high, but it is prone to occur extreme drought in northern, spring drought frequency of southwestern is relatively small while it is prone to occur severe drought.The strongest intensity and the maximum range of the spring drought has happened in 2000 and 2001.Spring drought time series in Henan exists significant interannual scale periodic variation and the intensity of these cycles are changes over time.(2)From the point of view of remote sensing drought monitoring:VSWI and soil relative humidity has a positive correlation, overall, VSWIe build the best, VSWIm followed, VSWIn is most unsatisfactory. In addition, the process of changes between precipitation and VSWI time seiers basically exhibited similar characteristic. VSWIe is the best of them. Finally, VSWI model which was based on EVI to monitor the spring drought of 2000 in Henan Province. So VSWIe is generally more suitable for monitoring Henan spring drought.(3)From the point of view of agricultural drought monitoring:in elongation-heading and grain-filling stage, water demand of winter wheat for larger, the crop water deficit index has a higher value, consequently, the frenquency of the spring drought is very high.Turning green to jointing and heading stage, winter wheat is in a rapid growth and reproductive growth stages, which is the most serious period of water deficit occurs.The frequency distribution of the winter wheat is very greatly, roughly latitudinal distribution, that is the water deficit index value gradually increasing from south to north.The frequency of spring drought in northern and western is highest in Henan, higher frequency of drought is in eastern area, southern with the lowest frequency. The trend of CWDI value of winter wheat in the southern show that:spring drought in Henan will increase to some extent.(4)From the point of view of soil moisture inversion model, the high value of soil moisture inversion model in Henan Province are mainly distributed in Zhoukou, Xinyang, Shangqiu and so on;the next are mainly distributed in Nanyang, Zhumadian and so on;the lowest districts are mainly located in Sanmenxia, Xinxiang and other places.